While various types of devices have been known for many years for effecting the removal of particulate matter from gases for various purposes, a significant advance in this art is represented by U.S. Pat. No. 3,596,885, which issued on Aug. 3, 1971. This patent discloses such a device which includes a rotatable impeller (wheel 21) which is used to establish a rapidly rotating curtain of scrubbing fluid at the outer periphery thereof. Furthermore, this curtain is then utilized to scrub a gas which is directed against that curtain at an acute angle to a plane normal to the axis thereof and opposed to the direction of rotation of the curtain of scrubbing fluid. In U.S. Pat. No. 3,596,885 this is accomplished by directing the gas from inlet 20 into an annular passage between inner and outer housings 10 and 11, where the rapidly rotating curtain of scrubbing fluid is located, and by directing the gas stream in the required manner by means of web 28, as shown in FIG. 3 thereof.
The apparatus and method disclosed in U.S. Pat. No. 3,596,885 has proven to be extremely valuable from a commercial standpoint. However, the search has continued for improvements in such a system, and the present application discloses a number of improvements which are applicable thereto.
Firstly, in connection with the concept of combining in a single apparatus means for impelling both a gas and a liquid, U.S. Pat. No. 3,478,496 to Keough discloses an impeller 40 located at the top of an exhaust stack 10 within enclosure 20. The fan redirects the gas from the stack outwardly within enclosure 20. In addition, however, part of the fan 40 defined by space 68 serves to produce a water jacket within the enclosure 20 as shown. However, contact with gas of any kind does not occur until the water jacket has cascaded downwardly under the force of gravity, and even then there is no passage of the gas through a rapidly rotating curtain of fluid, such as in the manner disclosed in the aforementioned U.S. Pat. No. 3,596,885. Also, U.S. Pat. No. 2,590,342 to Niehaus et al discloses an air washer including an impeller fan which rotates at high speed to atomize a stream of washing liquid so as to produce a fog of tiny liquid particles and force the gas through that fog. In particular, the patentee employs a fan 23 rotating at high speed to atomize washing liquid flowing through perforations 32 and conduit 29 so that the liquid and gas are simultaneously forced outwardly by fan 23. Again, there is no attempt to pass the gas stream to be scrubbed through a rapidly rotating curtain of scrubbing fluid.
British Pat. No. 681,609 to Jennings discloses yet another apparatus of this type, in this case for removing fine dust from blast furnace gas. This patentee employs a turbine-like apparatus including a series of discs 11 for rotation at high speed. Thus, water from feed distributor 19 is carried through holes drilled in collars 13 separating the discs 11 and emerges on the surface of each of the flat discs and spins outwardly therefrom to generate a dense curtain of water for contact with the gas passing therethrough. Again, no apparatus incorporating both a gas and scrubbing liquid impeller for forcing both gas and liquid outwardly is disclosed therein.
As for the nature of the scrubbing fluid impeller means itself, various references in a number of fields teach means for creating sprays of liquid and the like. Thus, U.S. Pat. No. 2,850,232 to Ingram discloses a centrifugal sprayhead, in this case for receiving paint, lacquer or other liquids, and to effect uniform distribution around the rotor thereof. In this case atomized particles are said to be produced by means of a sprayhead which includes a rotor body 6 having a central hub 7 so that liquid can be delivered to the hub bore 8. Thus liquid enters aperture 31 from bore 8 and finally through a series of apertures 36, strikes flange 41 so as to engage generally flat, annular surface 43, the outer periphery of which is bounded by wall 46 and finally to the rotor surface 48 including a plurality of grooves or slots extending over the conical surface thereof. Reference is also made to U.S. Pat. No. 3,765,688 to Junker, which relates to a fluid seal, but which does include a U-shaped channel member 12 and an annular baffle 18 projecting thereinto, further wherein oil delivered from nozzles 23 into channel member 12 can escape through bleed holes 24.
Additional patents relating to gas seals produced by liquids so as to confine a gas stream include, aside from the Junker patent, U.S. Pat. No. 3,694,042 to Rabenhorst, which discloses a liquid sealed in a radial fluid bearing, in this case including an annular member 34 positioned within a rotating annular flange 22 which retains fluid 14 therein through the action of centrifugal force. In addition, U.S. Pat. No. 1,949,429 to McGee discloses another type of fluid seal arrangement.